Patient-specific acetabular guides and associated instruments

ABSTRACT

A patient-specific acetabular guide can be used for preparing an acetabulum of a patient to receive an acetabular implant. The acetabular guide includes a patient-specific engagement surface designed to be complementary and mateable with a corresponding surface of the patient&#39;s pelvic anatomy. The acetabular guide is designed during a pre-operative plan for the patient by a three-dimensional reconstruction of the anatomy of the patient using two-dimensional medical images. The patient-specific engagement surface has a first portion mateable with a portion of the acetabulum of the patient. The acetabular guide includes a guiding element that extends from the acetabular guide opposite to the first portion of engagement surface. The guiding element defines a bore designed to be oriented along an alignment axis for an acetabular implant when the acetabular guide is engaged to the acetabulum.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional application61/446,660, filed Feb. 25, 2011.

This application is a continuation-in-part of U.S. application Ser. No.12/973,214, filed Dec. 20, 2010, which is a continuation-in-part of U.S.application Ser. No. 12/955,361 filed Nov. 29, 2010, which is acontinuation-in-part of U.S. application Ser. Nos. 12/938,905 and12/938,913, both filed Nov. 3, 2010, each of which is acontinuation-in-part of U.S. application Ser. No. 12/893,306, filed Sep.29, 2010, which is a continuation-in-part of U.S. application Ser. No.12/888,005, filed Sep. 22, 2010, which is a continuation-in-part of U.S.application Ser. No. 12/714,023, filed Feb. 26, 2010, which is acontinuation-in-part of U.S. application Ser. No. 12/571,969, filed Oct.1, 2009, which is a continuation-in-part of U.S. application Ser. No.12/486,992, filed Jun. 18, 2009, and is a continuation-in-part of U.S.application Ser. No. 12/389,901, filed Feb. 20, 2009, which is acontinuation-in-part of U.S. application Ser. No. 12/211,407, filed Sep.16, 2008, which is a continuation-in-part of U.S. application Ser. No.12/039,849, filed Feb. 29, 2008, which: (1) claims the benefit of U.S.Provisional Application No. 60/953,620, filed on Aug. 2, 2007, U.S.Provisional Application No. 60/947,813, filed on Jul. 3, 2007, U.S.Provisional Application No. 60/911,297, filed on Apr. 12, 2007, and U.S.Provisional Application No. 60/892,349, filed on Mar. 1, 2007; (2) is acontinuation-in-part U.S. application Ser. No. 11/756,057, filed on May31, 2007, now U.S. Pat. No. 8,092,465, issued on Jan. 10, 2012, whichclaims the benefit of U.S. Provisional Application No. 60/812,694, filedon Jun. 9, 2006; (3) is a continuation-in-part of U.S. application Ser.No. 11/971,390, filed on Jan. 9, 2008, now U.S. Pat. No. 8,070,752,issued on Dec. 6, 2011, which is a continuation-in-part of U.S.application Ser. No. 11/363,548, filed on Feb. 27, 2006, now U.S. Pat.No. 7,780,672, issued on Aug. 24, 2010; and (4) is acontinuation-in-part of U.S. application Ser. No. 12/025,414, filed onFeb. 4, 2008, which claims the benefit of U.S. Provisional ApplicationNo. 60/953,637, filed on Aug. 2, 2007.

This application is continuation-in-part of U.S. application Ser. No.12/872,663, filed on Aug. 31, 2010, which claims the benefit of U.S.Provisional Application No. 61/310,752 filed on Mar. 5, 2010.

This application is a continuation-in-part of U.S. application Ser. No.12/483,807, filed on Jun. 12, 2009, which is a continuation-in-part ofU.S. application Ser. No. 12/371,096, filed on Feb. 13, 2009, which is acontinuation-in-part of U.S. application Ser. No. 12/103,824, filed onApr. 16, 2008, which claims the benefit of U.S. Provisional ApplicationNo. 60/912,178, filed on Apr. 17, 2007.

This application is also a continuation-in-part of U.S. application Ser.No. 12/103,834, filed on Apr. 16, 2008, now U.S. Pat. No. 7,967,868,issued on Jun. 28, 2011, which claims the benefit of U.S. ProvisionalApplication No. 60/912,178, filed on Apr. 17, 2007.

This application is also a continuation-in-part of U.S. application Ser.No. 12/486,842, filed on Jun. 18, 2009, which is a continuation-in-partof U.S. application Ser. No. 12/358,664, filed on Mar. 24, 2009.

The disclosures of the above applications are incorporated herein byreference.

INTRODUCTION

The present teachings provide a patient-specific acetabular guide andrelated instruments for preparing an acetabulum to receive an acetabularimplant and guiding the implant into the acetabulum of a patient.

SUMMARY

The present teachings provide various instruments and methods forgenerally preparing the acetabulum of a patient to receive an acetabularimplant, such as, for example, an acetabular cup along an alignmentaxis. The alignment axis and various patient-specific guides andinstruments can be designed during a pre-operative plan using athree-dimensional reconstruction of the patient's relevant anatomy, suchas the pelvis or portions thereof, including the acetabular andperiacetabular areas of the pelvis. The three-dimensional reconstructioncan be based on two-dimensional medical images, including MRI, CT orX-ray scans and prepared using commercially available imaging software.

The present teachings provide, for example, an acetabular guide thatincludes a patient-specific engagement surface designed to becomplementary and mateable with a corresponding surface of the patient'spelvic anatomy. The acetabular guide is designed during thepre-operative plan for the patient using the three-dimensionalreconstruction of the anatomy of the patient. The patient-specificengagement surface has a first portion mateable with a portion of theacetabulum of the patient. The acetabular guide includes a guidingelement that extends from the acetabular guide opposite to the firstportion of engagement surface. The guiding element defines a boredesigned to be oriented along an alignment axis for an acetabularimplant when the acetabular guide is engaged to the acetabulum. Adrilling element with a stop can be used to drill a pilot hole into theacetabulum along the alignment axis.

The acetabular guide can be provided in various fitment options in whichthe patient-specific engagement surface is designed to fit in a uniqueposition relative to the patient anatomy. Each fitment option of theacetabular guide includes a portion that covers a center of theacetabulum for aligning the acetabular implant and additional portionscomplementary to a portion of the acetabular rim and/or a portion of thetransverse acetabular ligament. Each fitment option allows theacetabular guide to have a compact size, extend through the center ofthe acetabulum for alignment, and include portions that can fit overvarious anatomic landmarks in a unique position for the patient. Theparticular fitment option can be selected for each specific patientbased on the patient's anatomy, the procedure to be performed and thesurgeon's preference and/or technique.

In other embodiments according to the present teachings, the acetabularguide can include first and second marker elements extending from aportion of the acetabular guide outside the acetabulum of the patient.The marker elements define corresponding first and second bores forguiding first and second marker pins into a bone portion of the patient.A secondary guide can be used with the marker pins to orient anacetabular cup into a predetermined position and orientation. Thesecondary guide can be designed during the pre-operative plan to includefirst and second guiding elements complementary to the first and secondmarker elements of the acetabular guide for receiving the first andsecond marker pins when the first and second marker pins are attached tothe bone portion of the patient.

The acetabular guide can be used according to the present teachings witha guiding handle support device that can be attached to the pelvis andprovides an alignment rod as a reference for the alignment axis. Theguiding handle can be removably attached to the guiding element of theacetabular guide along the alignment axis. The support device caninclude a connector supporting the alignment rod. The connector can beremovably engaged with a shaft of the guiding handle. The support deviceincludes rotational and translational mechanisms for orienting thealignment rod parallel to the shaft of the guiding handle and parallelto the alignment axis such that the alignment rod can provide areference axis for the alignment axis.

The present teachings also provide a reamer having a guiding pin. Theguiding pin of the reamer can be received in the pilot hole that isdrilled in the acetabulum through the bore of the guiding element of theacetabular guide. The guiding pin is thus oriented along the alignmentaxis. In some embodiments, the reamer includes a spring that biases theguiding pin and provides tactile feedback during reaming. In someembodiments, the reamer includes a plurality of removable arcuateblades. The blades can be disposable or replaceable. In someembodiments, each blade is attached to a corresponding supportingelement shaped as a spherical section, such that the supporting elementscollectively form a surface corresponding to a shape of the acetabularcup.

The various instruments described above can be used in variouscombinations reaming the acetabulum and inserting an acetabular implantaccording to a pre-operative plan. In this regard the present teachingsprovide methods for reaming and preparing an acetabulum of a patient foran acetabular implant. One method includes engaging an acetabular areaof the patient with a complementary surface of a patient-specificacetabular guide, supporting an alignment rod on a support deviceattached to the patient's pelvis and orienting the alignment rod to beparallel to an alignment axis for inserting the implant. The alignmentaxis is determined during a preoperative plan of the patient andcoinciding with a center axis of a guiding element of the acetabularguide. The method further includes drilling a pilot hole in theacetabulum through a bore of the guiding element along the center axis,removing the acetabular guide, guiding an alignment pin of a reamer inthe pilot hole such that the alignment pin is parallel to the alignmentrod, and reaming the acetabulum.

Another method according to the present teachings includes engaging anacetabular area of the patient with a complementary surface of apatient-specific acetabular guide. The acetabular guide is designedduring a pre-operative plan from a reconstructed three-dimensional imageof the patient's anatomy. The method includes drilling a pilot hole inthe acetabulum through a bore of a guiding element of the acetabularguide along a patient-specific alignment axis determined by the guidingbore. The method also includes inserting first and second marker pinsinto an area outside the acetabulum of the patient through correspondingfirst and second marker elements of the acetabular guide. The methodincludes removing the acetabular guide without removing the marker pins,reaming the acetabulum, inserting an acetabular cup in the reamedacetabulum and sliding a secondary guide over the first and secondmarker pins. The method further includes engaging a planar arcuatesurface of the secondary guide to a complementary rim surface of theacetabular cup to align the acetabular cup to a position and orientationdetermined in the pre-operative plan.

Another method according to the present teachings includes using anelectronic positioner for guiding an acetabular inserter into theacetabulum along a predetermined patient-specific alignment axis. Theelectronic positioner is capable of indicating a predeterminedorientation using one or more orientation sensors. A patient-specificacetabular guide is placed on the acetabulum of the patient in a uniquemated position. The acetabular guide has a guiding element orientedalong the patient-specific alignment axis. A shaft of the acetabularinserter is inserted into the guiding element of the acetabular guide,such that the shaft of the acetabular inserter is oriented along thealignment axis. The electronic positioner is removably attached to theshaft of the acetabular inserter and is calibrated to indicate thealignment axis. After the acetabular guide is removed and the acetabulumprepared, the acetabular inserter with the acetabular implant can beguided along the alignment axis using feedback from the electronicpositioner.

Further areas of applicability of the present teachings will becomeapparent from the description provided hereinafter. It should beunderstood that the description and specific examples are intended forpurposes of illustration only and are not intended to limit the scope ofthe present teachings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present teachings will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIGS. 1-5 illustrate environmental perspective views of variouspatient-specific acetabular alignment guides according to the presentteachings;

FIG. 6 is an environmental perspective view of various instrumentsillustrating a method for establishing an acetabular cup insertion axisaccording to the present teachings;

FIG. 7 is an environmental perspective view illustrating drilling apilot hole for guided reaming according to the present teachings;

FIG. 8A is an environmental perspective view illustrating a reamer forguided reaming according to the present teachings;

FIG. 8B is a stylized perspective view of a reamer for guided reamingaccording to the present teachings;

FIG. 80 is a partially sectioned perspective view of the reamer of FIG.8B;

FIG. 9 is an environmental perspective view illustrating instruments forcup insertion according to the present teachings;

FIG. 10 is an environmental perspective view of a patient-specificacetabular alignment guide with alignment pins for a secondary guideaccording to the present teachings;

FIG. 11 is an environmental perspective view of another patient-specificacetabular alignment guide with alignment pins for a secondary guideaccording to the present teachings;

FIG. 12 is an environmental perspective view of the patient-specificacetabular alignment guide of FIG. 10 illustrating drilling a pilot holefor guided reaming according to the present teachings;

FIG. 13 is an environmental perspective view of a secondary guide overthe alignment pins of FIG. 10 according to the present teachings;

FIG. 14 is an environmental perspective view of a patient-specificacetabular alignment guide with an alignment pin and supportinginstruments according to the present teachings;

FIG. 15 is an environmental view of another embodiment of apatient-specific acetabular alignment guide shown with marker pinsaccording to the present teachings;

FIG. 16 is an environmental view of another embodiment of a secondaryguide shown with marker pins according to the present teachings;

FIG. 17 is an environmental view of another embodiment of a secondaryguide shown with marker pins according to the present teachings;

FIG. 18 is an environmental view illustrating a method of inserting anacetabular cup using the secondary guide of FIG. 16 according to thepresent teachings;

FIG. 19 is an environmental view illustrating another method ofinserting an acetabular cup using an acetabular inserter coupled to thesecondary guide of FIG. 16 with an adaptor according to the presentteachings;

FIGS. 20A and 20B are perspective views of a detail of coupling betweenthe acetabular inserter and the adaptor of FIG. 19;

FIG. 21 is a perspective view of another embodiment of an adaptor forcoupling an acetabular inserter to a secondary guide according to thepresent teachings;

FIG. 22 is an environmental perspective view illustrating calibrating anelectronic positioner coupled to an acetabular inserter and using apatient-specific alignment guide without marker pins according to thepresent teachings;

FIGS. 23A and 23B illustrate an acetabulum before and after reaming,respectively;

FIG. 24 is an environmental perspective view illustrating inserting anacetabular cup using the calibrated positioner of FIG. 22 according tothe present teachings;

FIG. 25 is an environmental perspective view illustrating calibrating anelectronic positioner coupled to an acetabular inserter and using apatient-specific alignment guide with marker pins according to thepresent teachings;

FIGS. 26A and 26B illustrate an acetabulum before and after reaming,respectively, using a secondary guide for alignment during reamingaccording to the present teachings;

FIG. 27 is an environmental perspective view illustrating inserting anacetabular cup using the calibrated positioner and secondary guide ofFIG. 25 according to the present teachings;

FIG. 28 is a perspective view of an electronic positioner coupled to anacetabular inserter/impactor as disclosed in commonly assigned U.S.Patent Publication 2010/0249796; and

FIG. 29 is a schematic view of the electronic positioner of FIG. 28.

DESCRIPTION OF VARIOUS EMBODIMENTS

The following description is merely exemplary in nature and is in no wayintended to limit the present teachings, applications, or uses.

The present teachings generally provide various patient-specificacetabular alignment guides, secondary guides, reamers, inserters,impactors and other associated instruments for use in orthopedicsurgery, such as in joint replacement or revision surgery, for example.The patient-specific alignment guides and associated instruments can beused either with conventional or with patient-specific implantcomponents prepared with computer-assisted image methods.

As described in commonly assigned U.S. application Ser. No. 11/756,057,filed on May 31, 2007, during a preoperative planning stage, imagingdata of the relevant anatomy of a patient can be obtained at a medicalfacility or doctor's office. The imaging data can include, for example,a detailed scan of a pelvis, hip, knee, ankle or other joint or relevantportion of the patient's anatomy. The imaging data can be obtained usingan MRI, CT, and X-Ray, ultrasound or any other imaging system. Theimaging data obtained can be used to construct a three-dimensionalcomputer image of the joint or other portion of the anatomy of thepatient and prepare an initial pre-operative plan that can include boneor joint preparation, including planning for resections, milling,reaming, broaching, implant selection and fitting, design ofpatient-specific guide, templates, tools and alignment protocols for thesurgical procedure.

Computer modeling for obtaining three-dimensional computer images of therelevant patient's anatomy can be provided by various CAD programsand/or software available from various vendors or developers, such as,for example, from Materialise USA, Plymouth, Mich. The computer modelingprogram can be configured and used to plan a preoperative surgical plan,including planning various bone preparation procedures, to select ordesign/modify implants and design patient-specific guides and toolsincluding patient-specific prosthesis components, and patient-specifictools, including reaming, broaching, milling, drilling or cutting tools,alignment guides, templates and other patient-specific instruments.

The pre-operative plan can be stored in any computer storage medium, ina computer file form or any other computer or digital representation.The pre-operative plan, in a digital form associated with interactivesoftware, can be made available via a hard medium, a web-based or mobileor cloud service, or a cellular portable device to the surgeon or othermedical practitioner, for review. Using the interactive software, thesurgeon can review the plan, and manipulate the position of images ofvarious implant components relative to an image of the anatomy. Thesurgeon can modify the plan and send it to the manufacturer withrecommendations or changes. The interactive review process can berepeated until a final, approved plan, is sent to a manufacturingfacility for preparing the actual physical components.

After the surgical plan is approved by the surgeon, patient-specificimplants and associated tools, including, for example, alignment guides,cutting/milling/reaming/broaching or other tools for the surgicalpreparation of the joint or other anatomy portion of the specificpatient can be designed using a CAD program or other three-dimensionalmodeling software, such as the software provided by Materialise, forexample, according to the preoperative surgical plan. Patient-specificguides and other instruments can be manufactured by variousstereolithography methods, selective laser sintering, fused depositionmodeling or other rapid prototyping methods. In some embodiments,computer instructions of tool paths for machining the patient-specificguides and/or implants can be generated and stored in a tool path datafile. The tool path data can be provided as input to a CNC mill or otherautomated machining system, and the tools and implants can be machinedfrom polymer, ceramic, metal or other suitable material depending on theuse, and sterilized. The sterilized tools and implants can be shipped tothe surgeon or medical facility for use during the surgical procedure.

Patient-specific implants, guides, templates, tools or portions thereofare defined herein as those constructed by a surgical plan approved bythe surgeon using thee-dimensional images of the specific patient'sanatomy and made to closely conform and mate substantially as a negativemold or negative surface or inverse or mirror surface of correspondingsurface portions of the patient's anatomy, including bone surfaces withor without associated soft tissue, such as articular cartilage, forexample, depending on the particular procedure, implant and tool use.

Patient-specific alignment guides and implants are generally configuredto match the anatomy of a specific patient and can fit in only oneposition on a corresponding surface of the specific patient becauseanatomic features that are unique to each patient function as landmarksand can guide placement of the alignment guide or implant in only oneposition without the need of intraoperative navigation, patient markingor other intraoperative guidance. The patient-specific alignment guidesare generally configured and manufactured using computer modeling basedon the patient's 3-D anatomic image and have an engagement surface thatis made to conformingly contact and match as a mirror or negative orinverse surface to a corresponding surface of a three-dimensionalimage/model of the patient's bone surface (with or without cartilage orother soft tissue), by the computer methods discussed above. Thepatient-specific alignment guides can include custom-made guidingformations, such as, for example, guiding bores or cannulated guidingposts or cannulated guiding extensions or receptacles that can be usedfor supporting or guiding other instruments, such as drill guides,reamers, cutters, cutting guides and cutting blocks or for insertingpins or other fasteners according to a surgeon-approved pre-operativeplan. The patient-specific alignment guides can be used in minimallyinvasive surgery, and also in surgery with multiple minimally-invasiveincisions. Various alignment guides and pre-operative planningprocedures are disclosed in commonly assigned and co-pending U.S. patentapplication Ser. No. 11/756,057, filed on May 31, 2007, U.S. patentapplication Ser. No. 12/211,407, filed Sep. 16, 2008; U.S. patentapplication Ser. No. 11/971,390, filed on Jan. 9, 2008, U.S. patentapplication Ser. No. 11/363,548, filed on Feb. 27, 2006; and U.S. patentapplication Ser. No. 12/025,414, filed Feb. 4, 2008. The disclosures ofthe above applications are incorporated herein by reference.

Referring to FIGS. 1-5, the present teachings provide variouspatient-specific acetabular guides 100, 200. The acetabular guides 100,200 can be used in connection with various other instruments tofacilitate guided reaming of an acetabulum 82 of a pelvis 80 of aspecific patient and guided insertion and implantation of an acetabularimplant or acetabular cup in the acetabulum 82. Further, thepatient-specific acetabular guides 100, 200 engage the acetabulum 82 ofthe specific patient in a unique (only one) position and can provide anaccurate alignment axis relative to the planned orientation of theacetabular cup 280 (shown in FIG. 9, for example). The patient-specificacetabular guides 100, 200 can also provide secure fitting androtational stability in a design that is lightweight with minimal sizeand bulk.

FIGS. 1-3 illustrate a patient-specific acetabular guide 100 having apatient-specific body 102, as described below, and a guiding or pilotelement 104 having an elongated bore 106 with a patient-specificalignment axis A for drilling a pilot hole on the acetabulum and/orestablishing the alignment axis A for a reamer, implant inserter,impactor or other instruments used in the preparation and implantationprocedure. The alignment axis A is configured to be central to theacetabular cup and perpendicular to the acetabular cup's surface whenthe acetabular guide 100 is positioned on the acetabulum 82. Thealignment axis A helps orient and guide the acetabular implant andvarious related instruments along a patient-specific orientationestablished during the pre-operative plan for the patient. Theacetabular guide 100 can be provided in various fitment optionsdepending on the planned exposure of the acetabulum 82 for the reamingprocedure and implantation. Each fitment option of the acetabular guidecan generally include a portion that covers a center of the acetabulumfor aligning the acetabular implant and additional portionscomplementary to a portion of the acetabular rim and/or a portion of thetransverse acetabular ligament. Each fitment option allows theacetabular guide 100 to have a compact size, extend through the centerof the acetabulum 82 for alignment, and include portions that can fitover various anatomic landmarks in a unique position for the patient.The particular fitment option can be selected for each specific patientbased on the patient's anatomy, the procedure to be performed and thesurgeon's preference and/or technique.

Three exemplary fitment options designated 100A, 100B and 100C areillustrated in FIGS. 1-3, respectively. The fitment options can includefitments engaging or registering to various combinations of portions ofthe acetabulum 82, the acetabular rim 84 and the transverse acetabularligament 83. For example, the acetabular guide 100 in the fitment option100A may engage a portion of the acetabulum 82, a portion of theacetabular rim 84 and a portion of the transverse acetabular ligament83. In the fitment option 100B, the acetabular guide 100 may engage aportion of the acetabulum 82 and a portion of the acetabular rim 84. Inthe fitment option 100C, the acetabular guide 100 may engage a portionof the acetabulum 82 and a portion of the transverse acetabular ligament83. Further details are discussed below. Either one or severalacetabular guides 100A, 100B, 1000 corresponding to different fitmentoptions can be provided to the surgeon for intra-operative flexibilityand plan change, according to the surgeon's preference. The acetabularguide 100 can be secured to the patient's bone with bone pins, guidewires or other fasteners.

The patient-specific body 102 of the acetabular guide 100 can include aninner portion 102 a (all fitment options) from which the guiding elementextends and which is designed to engage the acetabulum 82, an outerportion 102 b which extends from the inner portion 102 a and isconfigured to extend over a portion of the rim 84 (for fitment options100A and 100C) and an outer portion 102 c (fitment options 100A and1000) configured to extend over a portion of the transverse acetabularligament 83 (and adjacent area of the acetabulum 82). The patientspecific body 102 has an underside three-dimensional engagement surface108 that is custom-made or patient-specific to conform to and mirror (asa negative or inverse or mirror surface) complementary surfaces ofvarious combinations of the acetabulum 82, rim 84 and/or transverseacetabular ligament 83 or other periacetabular surfaces of the pelvis 80of the specific patient, as described above in connection with thevarious fitment options. The patient specific body 102 is designed byusing a three-dimensional image or model of the acetabulum 82 andsurrounding pelvic area of the patient, as described above. Theengagement surface 108 enables the acetabular guide 100 to nest orclosely mate relative to the complementarily acetabular surface of thepatient. The acetabular guide 100 can be designed to have generallysmall thickness, such that it can form a lightweight three-dimensionalshell from which the guiding element 104 extends opposite to theengagement surface. The guiding element 104 can be formed to be amonolithic or integral portion of the acetabular guide 100.Alternatively, the guiding element 104 can be modularly and removablycoupled to the acetabular guide 100, using, for example, a threadedconnection, snap-on connectors or other removable attachments.

Referring to FIGS. 4 and 5, another patient-specific acetabular guide200 is illustrated with exemplary two fitment options 200A and 200B.Similarly to the acetabular guide 100, the acetabular guide 200 alsoincludes a patient-specific body 202 and a guiding or pilot element 204having an elongated bore 206 with an alignment axis A configured to becentral to the acetabular cup and perpendicular to the acetabular cup'ssurface when the acetabular guide 200 is positioned on the acetabulum82. The acetabular guide 200 can include one or more marker elements 250(two are shown in the exemplary embodiments of FIGS. 4 and 5), eachhaving an elongated bore 252 for guiding marker pins 260. The markerpins 260 can be used for supporting a secondary guide for anotherpreparation method discussed below in reference to FIG. 12. The otherfeatures of the acetabular guide 200 are similar to that of theacetabular guide 100, such that the acetabular guide 200 can also beused instead of the acetabular guide 100. The acetabular guide 100 canbe used for procedures in which the marker elements 250 are notutilized, as described below. The acetabular guide 200 can be used forprocedures in which the marker elements 250 may or may not be utilized,as described below.

The patient-specific body 202 of the acetabular guide 200 is generallysimilar to patient-specific body 102 of the acetabular guide 100, suchthat the patient-specific body 202 can include an inner portion 202 afrom which the guiding element extends and which is designed to engagethe acetabulum 82, and an outer portion 202 b which extends from theinner portion 202 a and is configured to extend over a rim portion 84 ofthe acetabulum 82. The outer portion 202 b extends sufficiently beyondthe rim 84 to the periacetabular area of pelvis to accommodate themarker elements 250. The patient specific body 202 has an underside orbone-engaging three-dimensional engagement surface 208 that iscustom-made or patient-specific to conform and mirror (as an inverse ornegative or mirror surface) complementary surfaces of selected portionsof the acetabulum 82, the rim 84 and the transverse acetabular ligament83 (depending on the fitment option) or other periacetabular surfaces ofthe pelvis 80 of the specific patient by using a three-dimensional imageor model of the acetabulum and surrounding pelvic area of the patient,as described above. The engagement surface 208 enables the acetabularguide 100 to nest or closely mate relative to the complementarilyacetabular surface of the patient. The acetabular guide 200 can bedesigned to have generally small thickness, such that it can form alightweight three-dimensional shell from which the guiding element 204and marker elements 250 extend.

Referring to FIGS. 6-9, a method for reaming and preparing theacetabulum for an implant is described in connection with thepatient-specific acetabular guides 100. The acetabular guides 200 canalso be used, although the marker elements 250 are not utilized in thismethod. Referring to FIG. 6, a patient-specific acetabular guide 100 (or200) is placed in a unique position on the acetabulum/rim/transverseacetabular ligament depending on the fitment option and associatedanatomic landmarks of the patient, as determined in the preoperativeplan for the specific patient. Once positioned, the guiding element 104establishes the alignment axis A for the specific patient. An elongatedguiding handle 300 can be attached to the guiding element 104 such thatthe center axis of the guiding handle 300 coincides with the alignmentaxis A. The guiding handle 300 can include a proximal gripping portion302, an elongated shaft 304 extending from the gripping portion 302 anda coupling distal portion 306 which can be removably coupled to theguiding element 104, such that the guiding handle 300 is aligned alongthe alignment axis A. The connection can be a slidable or threadable orother connection between the distal portion 306 and the guiding element104. The distal portion 306 can include, for example, a bore 308 forreceiving the guiding element 104. The guiding element 104 and the bore308 can be of sufficient length for the guiding handle 300 to beremovably yet stably coupled to the guiding element 104 for indicatingthe alignment axis A without wobbling or other misaligning motion.

With continuing reference to FIG. 6, a support device or jig oroutrigger 400 can be secured on the pelvis 80. The support device 400can be used to orient an alignment pin or rod 402 along an axis A′parallel to the alignment axis A. More specifically, the support device400 can include a universal rotational adjustment mechanism 406 and apivotable/translational adjustment mechanism 408 for removably engagingthe shaft 304 and aligning the alignment rod 402 parallel to the shaft304 and, therefore, parallel to the alignment axis. In the exemplaryembodiment of FIG. 6, the support device 400 can include a leg 410 thatcan be attached to the bone with a bone fastener (not shown) through ahole 412 of a foot or base 414 of the leg 410. The support device 400can also include an arm 416 that is slidable coupled to the leg 410 toallow for translational motion of the arm 416 relative to the leg 410.The arm 416 can have, for example, an elongated slot 418 that slidablyreceives a fastener head 420 of a fastener 422, such as a screw or boltthat is received through a distal flange 424 of the leg 410. The flange424 can also pivot relative to the arm 416 about an axis B along theaxis of the leg 410 and fastener 422. The head 420 of the fastener 422can be rotated to lock the flange 424 and the leg 410 relative to thearm 416. The interconnection of the arm 416, the leg 410 and thefastener 422 collectively form the pivotable/translational adjustmentmechanism 408.

With continued reference to FIG. 6, the arm 416 can be substantiallyplanar and include at a distal end a housing 426 forming a socket 428for a ball 430 at a distal end of a connector 432. The socket 428 andthe ball 430 form a universal (ball) joint of the universal rotationaladjustment mechanism 406 for rotationally adjusting the connector 432relative to the arm 416. After adjustment, the orientation of theconnector 432 can be locked with a fastener 436 through the housing 426.The connector 432 supports the alignment rod 402 and includes anengagement surface 434 that can contact or engage the shaft 304, by asnap-on or other quick connect/disconnect connection. The support device400 can be adjusted using the adjustment mechanisms 406, 408 describedabove such that the alignment rod 402 along axis A′ is parallel to thealignment axis A of the shaft 304. In other words, the alignment rod 402can serve as a marker for the orientation of the alignment axis A toguide reaming and cup insertion procedures as discussed below.

After the support device 400 is locked in a position such that theorientation of the alignment rod 402 along axis A′ is fixed and parallelto the alignment axis A, the guiding handle 300 is disengaged from theengagement surface 434 of the connector 432 and the acetabular guide 100and is removed. Referring to FIG. 7, a drilling element 440 can beguided through the bore 106 of the guiding element 104 of the acetabularguide 100 to drill a pilot hole 89 in the acetabulum 82 along thealignment axis A, as shown in FIG. 8A. The drilling element 440 caninclude a stop 442 at a pre-determined position to prevent over drillingor drilling through the wall of the acetabulum 82. The depth of drillingand the location of the stop 442 on the drilling element 440 can bedetermined during the pre-operative plan for the specific patient. Thesupport device 400 and alignment rod 402 remain attached to the pelvisas shown in FIG. 6, although not fully shown in FIG. 7. After the pilothole 89 is drilled, the acetabular guide 100 is removed.

Referring to FIG. 8A, a reamer 500 can be guided along the alignmentaxis A to ream the acetabulum 82. Another embodiment of a reamer 500′according to the present teachings is illustrated in FIGS. 8B and 8C.The reamers 500 and 500′ can be used interchangeably and similarelements will be referenced with the same numerals herein below. Thereamer 500 (500′) can include a trocar or other guiding pin 502 that issized to fit and be received in the pilot hole 89 of the acetabulum 82for stabilizing and guiding the reamer 500 (500′) along the alignmentaxis A, i.e., at a predetermined location and orientation. This guidedreaming arrangement enables the surgeon to recreate the preoperativeplanned position and orientation for reaming the acetabulum 82 andimplanting the acetabular component. The alignment rod 402 which issupported by the support device 400 along the axis A′ that is parallelto the alignment axis A can also help to guide the reamer 500 (500′).

The reamer 500 (500′) can include a plurality of curved reaming blades504 and a supporting shaft 506 for a reamer driver or reamer handle. Thecurved blades 504 can be attached to a plurality of curved supportingelements 508 in the form of spherical leaves or sphericalsection/portions that collectively define a semi-spherical surfacecorresponding to the shape and size of the acetabular component to beimplanted in the acetabulum after reaming. The blades 504 can beremovable and replaceable or disposable. The entire reamer head thatincludes the blades 504 and the support element 508 can also bedisposable. A reamer 500 with four disposable blades 504 is illustratedin FIG. 8A, while the reamer 500′ shown in FIGS. 8B and 8C includes onlytwo reamer blades 504. Referring to FIG. 80, the guiding pin 502 can bespring biased to provide a tactile feedback during reaming. A spring orother biasing element 510 can be constrained between a proximal end 512of the guiding pin 502 and a wall 514 of the supporting shaft 506. A setscrew or fastener 516 can be used to stabilize the guiding pin 502 whileallowing slidable movement along the alignment axis during reaming. Thespring 510 can surround the fastener 516, as shown in FIG. 8C.Specifically, the fastener 516 is threaded to a blind bore 503 of theguiding pin 502 such that the fastener 516 and the guiding pin can movetogether along the alignment axis A by or against the action of thespring 510. The embodiments of FIGS. 8B and 80 also include a base ring518 integrally attached to the shaft 506 providing additional stability.

Referring to FIG. 9, after the acetabulum 82 has been reamed, anacetabular inserter 550 can be coupled to an acetabular cup 280 by anend coupler 552 at the distal end of a shaft 554 of the acetabularinserter 550. As seen in FIG. 9, the shaft 554 can be slidably andremovably coupled or engaged to the engagement surface 434 of theconnector 432 of the support device 400, such that the shaft is orientedand can slide along the alignment axis A for insertion of the acetabularcup 280 according to the preoperatively planned position andorientation. In some embodiments, the acetabular inserter 550 caninclude an impact head 520 and can be used to impact the acetabular cup280 after implantation.

Referring to FIGS. 10-13, another method of reaming and preparing theacetabulum 82 is illustrated using the acetabular guides 200 withfitment options 200A and 200B, as described above in connection withFIGS. 4 and 5. In this method, markers pins 260 are inserted through thecorresponding bores 252 of the marker elements 250 and attached to thebone in locations and orientations parallel to an axis B, as determinedduring the preoperative plan. The marker pins 260 can guide the locationof a secondary guide 600, shown in FIG. 13, and designed according tothe pre-operative plan to be guided by the marker pins 260, as discussedbelow.

The acetabular guide 200 can be slidably lifted off the marker pins 260and removed, leaving the marker pins 260 attached to the bone. Theacetabular cup 280 can be inserted using an acetabular inserter 550without the aid of an alignment orientation, although a support device400 with an alignment rod 402 can also be used if desired.

If desired, a reamer 500, 500 with a guiding pin 502 can be used to reamthe acetabulum 82, as discussed above in connection with FIG. 7,although other commercially available reamers can also be used. As wasdescribed above in connection with FIG. 7 and the acetabular guides 100,a pilot hole 89 of predetermined length is drilled into the acetabulum82 through the guiding element 204 with a drill element 440 until thestop 442 of the drilling element reaches the upper surface of theguiding element 204 of the acetabular guide 200.

After the acetabular cup 280 is inserted but not impacted, a secondaryguide 600 having secondary marker elements 650 with bores 652complementarily corresponding to the orientation and relative locationof the marker elements 250 of the acetabular guide 200 is placed overthe marker pins 260. The secondary guide 600 can be designed during thepre-operative plan such that the bores 652 are complementary to thelocation and orientation of the marker elements 250 of the acetabularguide. The secondary guide 600 can include extender elements 604supporting an arcuate or crescent-shaped planar flange 602 havingparallel inferior and superior surfaces 608, 610 designed during thepre-operative plan to be oriented parallel to a rim 282 of theacetabular cup 280, when the acetabular cup 280 is positioned in thepredetermined position and orientation. The orientation and position ofthe acetabular cup 280 is adjusted using the secondary guide 600, suchthat the planar flange 602 (and the inferior and superior surfaces 608,610 of the planar flange 602) and the rim 282 are parallel byascertaining contact and engagement of the planar flange 602 to the rim282 of the acetabular cup 280 in situ. It is noted that this method doesnot make use of the support device 400, although the acetabular guides200 can also be used with the supporting device, at the discretion ofthe surgeon. Depending on the surgeons preferences, any selected or allthe acetabular guides 100 (110A, 100B, 1000) and 200 (200A, 200B) andthe associated instruments including the reamer 500, 500′, thesupporting device 400, the drilling element 440 with the stop 442,alignment rod 402, marker pins 260 and the secondary guide 600 can beprovided in a surgical kit together with the acetabular cup 280 and/oradditional implants and instruments.

Referring to FIG. 14, another embodiment of the support device 400 issupport device 700 illustrated with a guiding handle 300′ and anacetabular guide 100 for positioning an alignment rod 402 in thepre-planned orientation A′. The support device 700 can be attached tothe bone with bone pins 703 that pass through arms 705. The arms 705extend slidably from a body 707 and can include scale markings 709 formeasuring distances from the body 707. The body 707 can include a planarslot 711 through which a first planar flange 713 can slidably pass therethrough and locked with a fastener (not shown) after adjustment. Thefirst planar flange 713 includes arms 715 pivotably connected to asecond planar flange 717 along a pivot axis coinciding with a centeraxis of a locking element 719. The locking element 719 can be used tolock the relative orientations of the first and second planar flanges713, 717. The second planar flange 717 can have a curved engagementsurface 721 for slidably engaging a shaft 304′ of the guiding handle300′. The shaft 404′ can include a groove 303 that is rotationally keyedto an element 721 extending from the second planar flange 717. Thesupport device 700 can provide pivotable and translational adjustabilityto align the alignment rod 402 parallel to the alignment axis A which isfixed when the shaft 304′ is attached to the guiding element 104 of theacetabular guide. The support device 700 can be used generally similarlyto the support device 400 to provide a reference axis A′ along thereference or alignment rod 402 to guide a reamer 500 or implant inserter550.

Referring to FIG. 15, another embodiment 200C of a patient-specificacetabular guide 200 is illustrated. Similarly to the embodimentsillustrated in FIGS. 4 and 5 discussed above, the acetabular guide 200Cincludes a patient-specific body 202 and a guiding or pilot element 204having an elongated bore 206 with an alignment axis A configured to becentral to the acetabular cup and perpendicular to the acetabular cup'ssurface when the acetabular guide 200 is positioned on the acetabulum82. The acetabular guide 200 can include one or more marker elements 250(two are shorn), each having an elongated bore 252 for guidingcorresponding marker pins 260. The marker pins 260 can be used forsupporting a secondary guide such as discussed below in reference toFIG. 12 above, or a secondary guide shown in FIG. 16.

The patient specific body 202 of acetabular guide 2000 is similar to thebody 202 of the acetabular guide 200A or 200B of FIGS. 4 and 5, andincludes a first portion 202 a from which the guiding element extendsand which is designed to engage the acetabulum 82, and a second portion202 b which extends from the inner portion 202 a and is configured toextend over a rim portion 84 of the acetabulum 82. The outer portion 202b extends sufficiently beyond the rim 84 to the periacetabular area ofpelvis to accommodate the marker elements 250. The patient specific body202 has an underside or bone-engaging three-dimensional engagementsurface 208 that is custom-made or patient-specific to conform to andmirror (as a negative or inverse or mirror surface) complementarysurfaces of selected portions of the acetabulum 82. In the embodiment ofFIG. 15, the patient specific body 202 includes additionally a thirdportion 202 c which conforms to and covers at least a portion of theacetabular fossa 85 of the acetabulum for providing additionalrotational stability. Further, an inferior edge 203 of the acetabularguide 2000 on the third portion 202 c is designed during thepreoperative plan to be parallel to the shape of the transverseacetabular ligament 83. The inferior edge 203 can provide an additionalvisual confirmation of correct alignment during positioning of theacetabular guide 200C on the acetabulum 82 of the patient.

Referring to FIG. 16, another embodiment of a secondary guide 600A isillustrated. The secondary guide 600A can be used with any of theacetabular guides 200 (200A, 200B, 2000). The secondary guide 600A canhave first and second (secondary) marker elements 650 with bores 652.The secondary guide 600 can be designed during the pre-operative plansuch that the bores 652 are complementary to the location andorientation of the marker elements 250 of the acetabular guide. Themarker pins 260 are secured into the bone through the marker elements250 of the acetabular guide 200, as shown, for example, in FIG. 10, anddiscussed above. The acetabular guide 200 is then lifted off the markerpins 260 and the secondary guide 600A is guided and placed over themarker pins 260. The secondary guide 600A is also designed during thepreoperative plan for the patient to have a guiding element 670 with alongitudinal bore 672 along an axis A′ that is parallel to the alignmentaxis A for the acetabular implant, when the secondary guide 600A isseated on the acetabulum over the marker pins 260, as shown in FIG. 16.Accordingly, an alignment pin 402 inserted into the bore 672 can serveas an indicator of the alignment direction A for reaming the acetabulumand inserting the acetabular cup.

As discussed above, the alignment axis A is the pre-operatively plannedaxis for insertion of the acetabular cup 280. Although the alignmentaxis A is shown, for simplicity, to coincide with the center axis ofvarious instruments used for inserting, reaming and impacting theacetabular cup 280, it should be appreciated that this designation isadapted to indicate the final positioning of the instrument in thedesired alignment. In other words, the alignment axis A and the axis ofthe instrument used are brought to coincidence by the methods describedherein and according to the present teachings.

In some embodiments of the secondary guide, such as the secondary guide600B shown in FIG. 17, the guiding element 670 may be placed in anoffset position relative to the secondary marker elements 650 to providebetter visualization of the acetabulum while guiding a reamer, inserter,impactor or other instrument along the alignment axis A parallel to thealignment pin 402.

Referring to FIGS. 18-20B, the acetabular inserter 550 coupled to theacetabular cup 280 can be guided along the alignment axis A by thealignment pin 402 of the secondary guide 600A (or the offset secondaryguide 600B), as an alternate method that does not use the support device400 described above and shown in FIG. 9. In some embodiments, an adaptor680, shown in FIGS. 19-20B, can be optionally used to couple theacetabular inserter 550 to the alignment pin 402 of the secondary guide600A, as a further aid to orient the acetabular inserter 550 along thealignment axis A. In particular, the adaptor 680 includes an arm 682,such as a cannulated shaft having a longitudinal bore 684 that receivesthe alignment pin 402 when the adaptor 680 is placed over the alignmentpin 402. Accordingly, the shaft 682 is aligned along the axis A′ that isdefined by the guiding element 670 of the secondary guide 600A. Theadaptor is coupled to a rotatable collar 560 of the acetabular inserter550 and secures the acetabular inserter 550 along the alignment axis Aparallel to the axis A′ of the shaft 682 and alignment pin 402. Theadaptor 680 can be coupled to the collar 560 with a tongue-in-groove orother keyed connection, as illustrated in FIGS. 20A and 20B. In someembodiments, for example, the collar 560 can include an extension 562forming a keyhole-shaped opening 565 with a first portion 564 having acircular cross-section and a second portion 566 having an elongatedcross-section. The keyhole opening 565 receives correspondingly shapedportions of the adaptor 680, forming a key 685 for the keyhole opening565 and preventing rotational movement. The key 685 has a firstcylindrical element 686 received in the first portion 564 of the opening565 and a second element 688 extending at a right angle from the firstelement 686 and received into the second portion 566 of the keyholeopening 565. Additionally, the key 685 and the keyhole opening 565 areangled at an acute angle relative to the alignment axis A and axis A′.Specifically, the first portion 564 of the keyhole opening 565 and thefirst element 686 of the key 685 are oriented along the direction of anaxis C forming an acute angle β with axes A and A′ as shown in FIGS. 20Aand 20B. This skewed orientation facilitates the insertion of the key685 into the keyhole opening 565 and the coupling of the adaptor 680 tothe acetabular inserter 550.

Referring to FIG. 21, in some embodiments 680A, the arm of 682 of theadaptor 680A can include an external V-shaped notch 690 instead of aninternal cannulation 684 of the embodiment 680 of FIGS. 20A and 20B,while retaining the key 685 for engagement with the keyhole opening 565of the acetabular inserter 550. The notch 690 can receive the alignmentpin 402 in a semi-constrained arrangement for facilitating engagementand disengagement between the adaptor 680A and the alignment pin 402.

Referring to FIGS. 22-29, various methods for preparing the acetabulumfor receiving an implant will be discussed in connection with the use ofelectronic positioners (800, 900) or other orientation devices forguiding the surgeon along the alignment axis A during reaming and/orinserting and impacting the acetabular implant into the acetabulum. Anycommercially available orientation sensing devices can be used for theelectronic positioner 800 (FIG. 22) or electronic positioner 900 (FIGS.28 and 29). Various embodiments of the electronic positioner 900 aredescribed in commonly assigned patent publications 2010/0249657, and2010/0249796, both published on Sep. 30, 2010, and incorporated hereinby reference. The electronic positioners can include a number ofgyroscopic sensors and/or accelerometers that can measure deviationsfrom a predetermined orientation and maintain or guide a return to thatorientation. In the context of the present teachings, the predeterminedorientation is the alignment axis A that was discussed above. Further,digital or MEMS gyroscopes of small size and capable of measuringdeviation about two or three sin axes can be used, such as, for example,a three-axis, single sensor digital gyroscope (model L3G4200D) availablefrom STMicroelectronics, Carrollton, Tex. It should be appreciated,however, that any combination of orientation sensors capable ofidentifying an orientation in three-dimensional space, includingcombinations of gyroscopic sensors (digital, analog, fiber optic orother type), having one or more axes, with other orientation sensors,such as accelerometers, such that the combination can identifydeviations from an axis in three-dimensional space. For example, a3-axis gyroscope (yaw, roll and pitch), or three one-axis gyroscopes, orone 2-axis gyroscope and one accelerometers, or three accelerometers orother combinations of gyroscopes and accelerometers. In someembodiments, the accelerometers can be single or multiple axesaccelerometers. Mechanical, piezoelectric, MEMS, analog or digitalaccelerometers and gyroscope can be used. Additionally, a miniaturizedcompass, a laser, and/or GPS device may be included with the electronicpositioner.

Referring to FIG. 22, the electronic positioner 800 can include ahousing 802 that is removably attachable to a shaft of an inserter,impactor, reamer or other instrument used in connection with theacetabular arthroplasty or other corrective procedure. In FIG. 22, theelectronic positioner is shown coupled to the acetabular inserter 550.The electronic positioner 800 can be, for example, keyed to the shaft554, slidably attached to the shaft 554 or the collar 560 of theacetabular inserter 800 or slip-fit or with a clamp-on ortongue-and-groove or other coupling arrangement. The housing 802 caninclude a controller/processor communicably coupled to the orientationsensor/sensors discussed above, and a feedback module. An exemplaryblock diagram for the electronic positioner 900 of FIG. 20 is shown inFIG. 29, described below, and can be used for the electronic positioner800, although the impact sensor and associated modules are optional andcan be omitted from the electronic positioner of 800.

The electronic positioner 800 can include a power or on/off button 806,a set button/input device 808 for setting a pre-determined orientationduring calibration and a set of LEDs 804 (outer set 804) for guiding theshaft 554 along the predetermined orientation (i.e., the alignment axisA) by lighting up to indicate a direction. The electronic positioner 800can also include an optional laser device 810 capable of providing areference orientation 812. The laser device 810 may be used, forexample, with accelerometers that measure in two non parallel directionsin a plane perpendicular to the reference orientation 812 of the laser.The electronic positioner 800 can be calibrated using one of thepatient-specific acetabular guides described above, such as, forexample, the acetabular guide 200C, shown in FIG. 22. The acetabularguide 2000 can be positioned at a unique position on the patient'sacetabulum, such that the guiding element 204 defines the alignment axisA, as designed during the preoperative plan. The shaft 554 of theacetabular inserter 550 can be slidably coupled to the guiding element204 as described above in reference to FIG. 6, for example, such thatthe longitudinal axis of the shaft 554 coincides with the alignment axisA.

With the shaft 554 of the inserter 550 aligned along the alignment axisA, and the electronic positioner 800 coupled thereon, the setbutton/input device 808 can be pressed or otherwise activated to set oridentify the alignment axis A as a reference axis, and store itsorientation. As the shaft 554 is moved, deviations from the referenceaxis can be calculated by the sensors (see 934, FIG. 29) of theelectronic positioner, processed by the controller (see 946, FIG. 29) ofthe electronic positioner and feedback provided by the LEDs 804indicating the direction and increment of deviation. For example, thedirection of deviation or, alternatively the direction to move tocorrect the deviation, can be indicated by the direction defined by alit LED, such as, for example, 804 b relative to a central LED 804 a,which lights up when the shaft 554 is correctly aligned along thereference/alignment axis A. In some embodiments, a relative amount ordegree of deviation for a given direction of a deviation can beindicated by a change in color of the LEDs 804, or by another set ofLEDs 803 (inner set) that light up at a different fixed color, forexample a fixed yellow to a fixed red of the outer set of LEDS 804. Itwill be appreciated that other types of feedback mechanisms orarrangements with or without LEDS and including visual, audio andvibratory or tactile feedback can be used, as disclosed in patentpublications 2010/0249657 and 2010/0249796, referenced above, andfurther discussed below in reference to FIGS. 28 and 29.

After the electronic positioner 800 is calibrated, the surgeon may reamthe acetabulum 82 using a surgeon-selected method or any of the methodsdiscussed above. See, for example, FIG. 8A and associated discussion.FIGS. 23A and 23B illustrate the patient's acetabulum 82 before andafter reaming, respectively. After reaming, the acetabular inserter 500with the electronic positioner 800 thereon can be coupled to theacetabular implant 280, as shown in FIG. 24, for inserting theacetabular implant 280 along the predetermined alignment axis A, asguided by the electronic positioner 800. Feedback from the LEDs 804and/or 803 or other feedback mechanism can help guide the surgeon tocorrect any deviation from the predetermined alignment axis A thatcoincides with the calibrated reference axis of the electronicpositioner 800, as discussed above.

When using the electronic positioner 800, as described above, markerpins 260 and a secondary guide 600, 600A, 600B are not necessary.Depending on the surgeon's preference, when additional guidance isdesired, the marker pins 260 and the secondary guide 600A (or 600 or600B) can be used together with the electronic positioner 800, asillustrated in FIGS. 25-27. The marker pins 260 can be inserted, forexample, through the marker elements 250 of the patient-specificacetabular guide 200C, as shown in FIG. 25 during calibration of theelectronic positioner 800. After calibration, the patient-specificacetabular guide 2000 is lifted off the marker pins 260, which are leftattached to the acetabulum 82 for guiding the placement of the secondaryguide 600A (or 600B or 600), as shown in FIG. 26A. The alignment pin 402can be used as a reference for the implant alignment axis A. In someembodiments, the alignment pin 402 can be used to align a supportingshaft 506 of a reamer 500 (see FIG. 8A) parallel to the direction A′ ofthe alignment pin 402 and used during reaming. After reaming, thesecondary guide 600A and the marker pins 260 can remain attached to theacetabulum, as shown in FIG. 26B, to further guide the surgeon duringthe insertion of the acetabular cup 280. Accordingly, and referring toFIG. 27, the alignment pin 402 of the secondary guide 600A can providean initial reference direction A′ for the surgeon to position theacetabular inserter 800 easier and quicker along the alignment directionA, and make smaller corrections in orientation with the help of the LEDs804, 803 or other feedback mechanism of the electronic positioner 800.

Referring to FIGS. 28 and 29, the electronic positioner 900 of the abovereferenced patent publications 2010/0249657 and 2010/0249796 is brieflydescribed. It will be appreciated that in some embodiments, theelectronic positioner 900 can replace the electronic positioner 800 inthe methods described above. In other embodiments, the electronicpositioner 800 can incorporate all or some of the functions of theelectronic positioner 900, while maintaining, for example, the geometryof the housing 802 and the LED feedback arrangement described above inreference to FIG. 22. In some embodiments, the electronic positioner 800can include a orientation sensor (or sensors) 934, but not impactsensors 947 and impact feedback, as discussed below. In otherembodiments, the electronic positioner 800 may also include the impactsensor 947 and associated feedback mechanisms of the electronicpositioner 900.

As shown in FIGS. 28 and 29, the electronic positioner 900 can include acylindrical housing 926 coupled to an acetabular inserter/impactor tool916 having a longitudinal shaft 918. Specifically, the housing 926 caninclude a passage 930 that receives the shaft 918 and couples thehousing 926 to the acetabular inserter/impactor tool 916 in a fixedposition relative to the shaft 918. The housing 926 can include a seamor hinge or other longitudinal separator 931 between first and secondsportions 932 a, 932 b of the housing 926 for removing the housing 926from the shaft 918. In some embodiments, the hinge 931 can operate tosecure the first and second portions 932 a, 932 b in a clam shell designof the housing 926.

It will be appreciated that the housing 926 can be attached to the shaft918 in any suitable fashion, such as an interference fit, a taper totaper fit between the shaft 918 and the inner surface of the passage930, or other arrangement. In some embodiments, the shaft 918 caninclude a recess (not shown) that receives the housing 926 such that thehousing 926 is in a fixed position relative to the shaft 918. Further,the electronic positioner 900 can be removably coupled to variouscommercially available inserter/impactor tools 916, such as a RingLoc®Inserter (Part No. S313141) or a Magnum Inserter (Part No. 313131),commercially available from Biomet Manufacturing Corp., of Warsaw, Ind.The electronic positioner 900 can be similarly coupled to the shaft ofthe inserter 550 or reamer 500 or guiding handle 300 or other tool usedduring the acetabular procedure for guiding along the alignment axis A.

As shown in FIGS. 28 and 29, the electronic positioner 900 can includeone or more orientation sensors 934. The orientation sensor 934 candetect an actual orientation of the longitudinal axis of theinserter/impactor tool 916 relative to a reference orientation orreference vector, such as the force of gravity. In some embodiments, theorientation sensor 934 can detect acceleration about three separateorthogonal axes (accelerometer sensors) or angular velocity (spin) aboutone or more orthogonal axes (gyroscopic sensor), as discussed above inreference to the electronic positioner 800.

The electronic positioner 900 (or 800) can include an orientationfeedback device 936. The orientation feedback device 936 can selectivelyprovide an orientation feedback signal when the actual orientation ofthe inserter/impactor tool 916 is substantially equal to a predeterminedtarget orientation, i.e., the alignment axis A discussed above. Thefeedback signal provided by the orientation feedback device 936 canautomatically indicate to the surgeon that the inserter/impactor tool916 is in the target orientation, such that the acetabular cup can beproperly positioned and implanted for added convenience and accuracy.

As represented in FIG. 29, the orientation feedback device 936 caninclude an audible feedback device 938 that emits an audible feedbacksignal. For instance, the audible feedback device 938 can include aspeaker that emits a preprogrammed sound when the inserter/impactor tool916 is in the target orientation. Furthermore, the orientation feedbackdevice 936 can include a visual feedback device 940 that emits a visualfeedback signal. For instance, the visual feedback device 940 caninclude one or more lights, such as LED lights, for emitting apreprogrammed light pattern when the inserter/impactor tool 916 is inthe target orientation. An embodiment of the visual feedback device 940is described above in connection with the LEDs 804 and 803 of theelectronic positioner 800. Additionally, the orientation feedback device936 can include a tactile feedback device that selectively emits atactile feedback signal when the inserter/impactor tool 916 is in thetarget orientation. For instance, the tactile feedback device 942 caninclude a vibration motor that selectively vibrates the housing 926 andthe inserter/impactor tool 916 when the inserter/impactor tool 916 is inthe target orientation.

It will be appreciated that the orientation feedback device 936 canprovide any suitable feedback signal, including combinations of visual,audible and tactile feedback. Also, it will be appreciated that thefeedback signal can be seen, heard, and felt simultaneously, and thisredundancy can increase accuracy and convenience.

The electronic positioner 900 (or 800) can include a controller 946. Thecontroller 946 can include various components, such as a microprocessor,memory, and the like. The controller 946 can be in communication withthe orientation sensor 934 and the orientation feedback device 936.Accordingly, the controller 946 can cause the orientation feedbackdevice 936 to selectively provide the respective orientation feedbacksignal(s) when the actual orientation of the inserter/impactor tool 916detected by the orientation sensor 934 is substantially equal to apredetermined target orientation of the inserter/impactor tool 916.

The electronic positioner 900 (or 800) can include an impact sensor 947to help the surgeon determine more accurately and conveniently when theacetabular cup 280 is fully seated in the acetabulum 82 of the patient.The impact sensor 947 can detect an actual impact effect on theinserter/impactor tool 916. For instance, the impact sensor 947 can beconfigured to detect an actual impact force F_(i) on the head 920 of theinserter/impactor tool 916. The impact sensor 947 can also detect anactual displacement of the inserter/impactor tool 916 when the loadF_(i) is applied to the head 920. In addition, the impact sensor 947 candetect an actual acoustic effect of the impact when the load F_(i) isapplied. It will be appreciated that the impact sensor 947 can beconfigured to detect any suitable effect of applying the load F_(i). Theimpact sensor 947 can include any suitable component, such as anaccelerometer and/or a piezoelectric sensor, for detecting the actualimpact effect. It will be appreciated that the orientation sensor 934and the impact sensor 947 can rely, at least in part, on some of thesame components, such as a common accelerometer, for the respectivefunctions.

With continued reference to FIGS. 28 and 29, the electronic positioner900 (or 800) can include an impact feedback device 948. Generally, theimpact feedback device 948 can provide a feedback signal when the actualeffect of applying the load F_(i) detected by the impact sensor 947substantially matches a predetermined target impact effect. Morespecifically, the surgeon can predetermine a target impact effect (e.g.,a predetermined impact force F_(i), an amount of displacement, anacoustic effect, etc.) that correlates to a condition in which theacetabular cup 280 is fully seated in the acetabulum 82 of the patient.Then, the controller 946 can cause the impact feedback device 948 toprovide the respective feedback signal when the actual impact effectsubstantially matches the predetermined target impact effect. Thus, theimpact feedback device 948 can inform the surgeon that the acetabularcup 280 has been fully seated into the acetabulum 82 of the patient.

It will be appreciated that the impact feedback device 948 can includeany suitable device, such as an audible feedback device 950, a visualfeedback device 952, and/or a tactile feedback device 954. The audiblefeedback device 950 can provide an audible feedback signal, and caninclude a speaker or any other suitable device for providing an audiblefeedback signal. The visual feedback device 952 can provide a visualfeedback signal, and can include one or more lights, such as LED lights,for providing a visual feedback signal. Also, the tactile feedbackdevice 954 can provide a tactile feedback signal and can include avibration motor that selectively provides a tactile feedback signal.

In some embodiments, the electronic positioner 900 (or 800) can includean input device 941 for manually setting the target orientation of theinserter/impactor tool 916. More specifically, the input device 941 caninclude buttons, dials, a display, and other features for setting atarget inclination angle, a target anteversion angle, or any othersetting for the orientation of the alignment axis A. The input device 41can be integrally coupled to the housing 926, and/or the input device941 can be separate and remote from the housing 926. For example, asshown in FIG. 28, the input device 941 can include a wirelesstransmitter 943, and the housing 926 can include a wireless receiver945. The receiver 945 receives wireless signals from the transmitter 943to thereby set the target orientation of the alignment axis A. In someembodiments, the input device 941 can include an alphanumeric keypad formanually inputting and setting a particular target orientation.Additional details about of the electronic positioner 900 can be foundin patent publications 2010/0249657 and 2010/0249796, referenced above,and are or can be similarly incorporated in the electronic positioner800.

Various patient-specific guides, secondary guides, reamers, guidehandles, inserters, impactors, support devices, electronic positionersand other instruments can be used in various combinations and based onsurgeon preferences or patient and preoperative or intraoperativecircumstances for preparing an acetabulum and guiding and implanting anacetabular implant along a preoperatively determined alignmentorientation. In this respect, tools and instrumentation providingredundant functionality and of different embodiments may provided to thesurgeon in a kit or per surgeon's request. For example, more than onepatient specific acetabular guide (100, 200) may be provided. Similarly,various support devices (400, 700), secondary guides (600, 600A, 600B),reamers (500, 500′), inserters and/or impactors (550, 916), adaptors orcouplers, electronic positioners (800, 900) and other instrumentsdescribed above can be provided and used in various combinations withinthe scope of the methods described herein.

The foregoing discussion discloses and describes merely exemplaryarrangements of the present teachings. Furthermore, the mixing andmatching of features, elements and/or functions between variousembodiments is expressly contemplated herein, so that one of ordinaryskill in the art would appreciate from this disclosure that features,elements and/or functions of one embodiment may be incorporated intoanother embodiment as appropriate, unless described otherwise above.Moreover, many modifications may be made to adapt a particular situationor material to the present teachings without departing from theessential scope thereof. One skilled in the art will readily recognizefrom such discussion, and from the accompanying drawings and claims,that various changes, modifications and variations can be made thereinwithout departing from the spirit and scope of the present teachings asdefined in the following claims.

What is claimed is:
 1. A method for reaming and preparing an acetabulumof a patient for an acetabular implant, the method comprising: engagingan acetabular area of the patient with a complementary surface of apatient-specific acetabular guide; supporting an alignment rod on asupport device attached to the patient's pelvis; orienting the alignmentrod to be parallel to an alignment axis for inserting the acetabularimplant, the alignment axis determined during a preoperative plan of thepatient and coinciding with a center axis of a guiding element of theacetabular guide; drilling a pilot hole in the acetabulum through a boreof the guiding element along the center axis; removing the acetabularguide; guiding an alignment pin of a reamer in the pilot hole such thatthe alignment pin is parallel to the alignment rod; and reaming theacetabulum.